Process for detoxicating exhaust gases from otto-combustion engines and apparatus for carrying out such process

ABSTRACT

Exhaust gases emanating from an internal combustion engine, such as an Otto-cycle engine, have a swirl imparted thereto by a twist generator to expand the exhaust gases and to reduce the pressure thereof. Air is aspirated into the expanded exhaust gases for admixture therewith to provide a combustible gas-air mixture which is delivered to a diffusor for after-burning of the toxic ingredients of the exhaust gases with an increase in pressure of the products of combustion. The exhaust gases flowing to the twist generator pass through a heat exchanger serving to preheat the combustion air. The twist generator may be a set of stationary whirl-imparting vanes, or may be the rotor of an exhaust gas turbo charger directly driving an air compressor which delivers the air through the heat exchanger to the turbo charger, with some of the compressed air being delivered back to the engine. The flow area of the outlet of the twist generator is adjustable to adjust the quantity of air aspirated into the exhaust gases supplied to the diffusor.

United States Patent [1 1 Klaue et a].

[ PROCESS FOR DETOXICATING EXHAUST GASES FROM OTTO-COMBUSTION ENGINESAND APPARATUS FOR CARRYING OUT SUCH PROCESS [75] Inventors: Hans JoachimKlaue; Josef Reisacher, both of Frankenthal, Germany [73] Assignee:Aktiengesellschaft Kuhnle, Kapp &

Kausch, Frankenthal, Germany 22 Filed: Apr. 30, 1971 21 Appl.No.:139,157

[4 1 Mar. 12, 1974 Kadenecy 60/13 Bertin et al. 60/13 5 7 ABSTRACTExhaust gases emanating from an internal combustion engine, such as anOtto-cycle engine, have a swirl imparted thereto by a twist generator toexpand the exhaust gases and to reduce the pressure thereof. Air isaspirated into the expanded exhaust gases for admixture therewith toprovide a combustible gas-air mixture which is delivered to a diffusorfor after-burning of the toxic ingredients of the exhaust gases with anincrease in 'pressure of the products of combustion. The exhaust gasesflowing to the twist generator pass through a heat exchanger serving topreheat the combustion air. The twist generator may be a set ofstationary whirl-imparting vanes, or may be the rotor of an exhaust gasturbo charger directly driving an air compressor which delivers the airthrough the heat exchanger to the turbo charger, with some of thecompressed air being delivered back to the engine. The flow area of theoutlet of the twist generator is adjustable to adjust the quantity ofair aspirated into the exhaust gases supplied to the diffuser.

3 Claims, 7 Drawing Figures PAIENIEMm m4 3,796,046

sum 1 or 3 INVENTORS HHNS U'OHcHM kmos, abswwsacm msmmumwm 3.796046SHEET 2 OF 3 INVENTORS HANS voncnM KLnvE, UosEF REISBcusk BY: WIMMHTTORNEY 4 PROCESS FOR DETOXICATING EXHAUST GASES FROM OTTO-COMBUSTIONENGINES AND APPARATUS FOR CARRYING OUT SUCH PROCESS SUMMARY OF THEINVENTION The invention concerns a process for detoxifying exhaust gasesfrom Otto-engines and apparatus for carrying out this process.

The purpose of such a process is to eliminate toxic but stillcombustible portions of carbon monoxide and CPI-compounds, present inexhaust gases of Ottoengines, through an after-combustion step.

Processes and devices for carrying out after combustion were heretoforeknown and are usually connected to the exhaust pipe system of theOtto-engine. These known combustion systems or plants have thedisadvantage that they require a combustion chamber with extensiveequipment, particularly an air delivery pump which feeds the requiredair into the exhaust gases to effectuate the combustion. I

The present invention is based on the task of detoxicating exhaust gasesand of developing an apparatus and instrumentalities which areconsidered markedly simplified and radically less expensive thanheretofore known detoxicating and after combustion systems. The solutionof such problem pursuant to the invention by means of a process fordetoxifying exhaust gases from Otto-combustion engines is characterizedin that the exhaust gases are first expanded to create a relatively lowpressure (underpressure) between a twist generator and a diffusor, sothat combustion air is sucked in by the partial vacuum formed, and thatthe after combustion step takes place in the diffusor in which thepressure will rise again. r

When the air required for the after combustion is sucked in, a thoroughmixing of exhaust gas and air is effectuatcd so that the aftercombustion becomes substantially complete in the subsequent diffusorpart of the novel apparatus.

Another improvement of the after combustion is achieved according to theinvention in thatthe turbine rotor of a waste or exhaust gasturbo-supercharger is used as a twist generator for bringing about theexpan-' sion of the exhaust gases, this turbine driving a compressor,which delivers the air for the after combustion process. The compressedair introduced into the cycle mixes particularly well with the exhaustgases so that, when an exhaust gas turbo-supercharger is used,practically all harmful constituents of the exhaust gas are burnt anddisposed of.

The use of an exhaust gas turbo-supercharger has the further advantagethat the Otto-engine can be supercharged, so that the performance andoutput of the Otto-engine is increased.

Preferably a heat exchanger is arranged in the path of the exhaust gasbetween the Otto-engine and the twist generator, to effect preheating ofthe air required for the after combustion.

A plant or apparatus for carrying out the process pursuant to theinvention has preferably a stationary twist generator provided withguide vanes or blades after which is arranged e.g., a radial diffusoracting as an after combustion chamber.

One of the important objects of the invention is to provide meansachieving a highly desirable, more economical and complete burning ofthe toxic constituents of exhaust gases.

A further object and advantage of the invention is to provide meansresulting in the employment of the exhaust turbo supercharger on one andthe same drive shaft as a turbine for the exhaust gases, whereby theturbine functions as a radial or diagonal turbine with external orperipheral intake and axial discharge. The blade wheel of the turbineserves in such case as a twist generator which is non-stationary, towhich is subsequently disposed a radial diffusor near the discharge endof the turbine blade wheel.

These and other advantageous features and characteristics of theinvention are derived from the drawings and claims.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 shows in block diagram one ofseveral possible processes pursuant to the invention;

FIG. 2 is an axial sectional view of a stationary twist generator;

FIG. 3 shows the development of a cylinder section through blades of thetwist generator;

F IG' 4 is a further block diagram illustrating the employment of anexhaust-gas turbo-supercharger in a preferred process;

FIG. 5 is an axial sectional view of the turbine of an exhaust gasturbo-supercharger to which a radial diffusor is connected in series;

FIG. 6 is a longitudinal sectional view through a part of an exhaustsystem which is used as a heat exchanger; and i FIG. 7 is a sectionalview taken along line 7 7 of FIG. 6.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS Referring now morespecifically to the attached drawings, M denotes the Otto-engine, A theexhaustgas-carrying lines and L the air-feed lines. The exhaust gasesare conducted from the piston engine M via the heat exchanger WT to thetwist generator DE, where they are expanded. Subsequently they enter thediffusor NB which serves and is designed as an after-burner.

. The air required for the after-combustion flows via the heat exchangerWT, in which it is heated up by means of the exhaust gas heat, to thetwist generator DE and thence mixing with the exhaust gases thoroughlyinto the afterburner, where the toxic constituents of the exhaust gas,CO- and CPI-compounds are burnt.

FIG. 2 shows in axial section through an embodiment constituting a twistgenerator 101 with a radial diffusor 102 and a control shield or device106, which has a wall 118 facing the twist generator and a further wall117 remote thereof, and which is axially displaceable in order toregulate and check the size of the effective outlet cross section 109for the gas flow from the twist generator 101.

The twist generator is connected directly to the'exhaust line, forexample, by means of flange 105. The exhaust gases arriving from theengine flow to the twist generator 101 and are set in rotation by theguide blades 116 (see arrow in FIG. 3) Their velocity will be increasedmore or less depending on the relative axial position of the controldevice 106. According to the theorem of Bernoulli the static pressure incross section 109 can be reduced so far that the air is sucked inthrough slot 107 which remains between the two walls 117,118. The supplyof air can take place as indicated by arrows 108, after the air has beenheated preferably in a heat exchanger (not shown).

The exhaust gas-air mixture enters then subsequently with great twirlthe radial diffusor 102 which serves at the same time as anaftercombustion chamber. Due to the thorough and intimate mixing of theexhaust gases with air on the basis of great turbulence effected by thestrong twirl, the combustion of the toxic CO- and CH- constituents ofthe exhaust gases becomes practically complete. An air pump is notrequired and is dispensed with according to the invention.

The regulation of the twirl by the axial displacement of the wall 118permits an optimum adjustment on one hand of the air intake, and of theback pressure of the exhaust gases on the other hand toward the engine.

Furthermore means or instrumentalities can be provided with respect tothe diffusor 102 designed as an after-combustion chamber which permits aprimary ignition and/or a stabilization of the flames in a criticalstate of operation.

The process and plant for detoxifying the exhaust gases according to theinvention have the great advantage that the various functions explainedhereinabove are performed in a minimum of space with a minimum number ofparts and without any moving parts for the essential operational steps.No auxiliary devices or accessories are required for delivering the air.The plant or apparatus described is thus simple and inexpensive and itsoperation is safe and highly economical.

FIG. 4 shows in block diagram a process according to the inventionemploying an exhaust gas turbosupercharger as a twist generator.

M denotes the Otto-engine, A the exhaust-gascarrying lines, L theair-supply lines. The exhaust gases are conducted from the Otto-enginevia the heat exchanger WT to the turbine T of the exhaust gasturbosupercharger, where they are expanded. From the turbine they areled into the afterburner NB. The turbine drives the compressor V of theexhaust gas turbo supercharger which delivers the air to a manifold ordistributor U. The air required for the after-combustion flows via theheat exchanger WT, in which it is heated by means of the exhaust gasheat, into the afterburner NB, where it burns the toxic constituents ofthe exhaust gas, namely, carbon monoxide and the CPI-compounds. A partof the air may be conducted from the manifold U to the engine M forsupercharging. In stages of operation which are outside the range of theexhaust gases or where there is no danger that toxic constituents arecontained in harmful quantities in the exhaust gas, the entire or-alarge quantity of charging air may be used for increasing the output ofthe engine.

FIG. 5 shows an axial section through the turbine of an exhaust gasturbo-supercharger which can be used,

sufficiently high and possibly uniform charging pressure for differentspeeds and different loads of the Otto engine; The regulation may alsobe effected additionally by varying the flow cross section with respectto the inlet-spiral of the turbine.

The air supplied for the after-combustion is introduced, in the turbineaccording to FIG. 5, into a chamber 8 around control element 2 throughinlet openings (8a). From there it flows through bores 13 into theinterior, as indicated by the respective arrows.

The control device 6 consists, in this embodiment, of

a wall 17 facing the turbine wheel and of a wall 18 remote of thiswheel. Between these two walls there are disposed slots 19 along thecircumference of the walls. The air for the gas combustion, which flowsthrough the bores 13 in axial direction along chamber 20 of the controldevice 6, passes through these slots 19 out of the control device 6. Theexhaust gases from the turbine wheel are forced to flow at high velocitythrough the cross section 15 between the outlet edge 9 of the wheel andwall disk 17 of the control device 6. They produce thus at the slots 19a suction effect, so that the air is additionally sucked in.

After combustion air (arrow 16a) may also be supplied from chamber 16 onthe rear side of the turbine wheel 5. This results in the furtheradvantage that the hot turbine wheel 5 will be cooled, which permitsunder certain circumstances the use of a less heat-resistant and thuscheaper material for the turbine wheel 5.

The exhaust gas turbo charger represented in FIG. 5 has a radial,diffusor 4 which permits a particularly effective utilization of theexhaust gas energy by reducing the outlet pressure, if necessary, evenbelow atmospheric pressure. This radial difiusor serves at the same timeas an afterburner, and a practically complete combustion of the toxicconstituents is achieved by the annular splitting of the exhaust gasflow and the annular dosed admixture of after combustion air.

The radial diffusor increases the suction effect at slots 19, so that agreater pressure gradient is available for the admixture than forsupercharging the engine. This is of particular advantage for the idlerun where the supercharge anyway does npt occur through the action ofthe throttle valve.

Means may also be provided which permit a first or initial ignition or astabilization of the flame in critical operating ranges.

A particularly advantageous design was created for the heat exchanger ofthe process according to the invention. It is characterized in that apart of the exhaust pipe 21 or of the turbine housing 1 or generally,the housing of the twist generator and of the diffusor, is designed as aheat exchanger for treating the after combustion air. I

FIGS. 6 and 7 show an embodiment employing the exhaust pipe 21 for'thispurpose. FIG. 6 represents a longitudinal section through a part of theexhaust system of the engine, where the exhaust pipe is arranged closelyenough to the cylinder block 22, so that a boundary surface is formed bythe latter. The substan tially semicircular shell of the exhaust pipe 23is surrounded by a substantially semicircular jacket 24. The space 25between pipe 23 and jacket 24 is then traversed by the air available forthe after-combustion entering through inlet 25a and leaving throughsocket 25b and a good heat exchange is achieved on account of therelatively large contact surface and the high velocities.

In the exhaust gas turbocharger according to FIG. 5 the turbine housing1 is surrounded by a jacket 14. The interspace is traversed by the aftercombustion air which is preheated by the relatively hot turbinehousing 1. The air enters through inlet 7a into the interspace 7.

The process and the plant for detoxificating exhaust gases according tothe invention have the advantage in that a substantially completeburning of the toxic constituents of the exhaust gas is afforded so thatpractically no carbon monoxide and no Cl-l-compound remain anymore.Since the aftercombustion takes place in the exhaust gas-turbine of theturbocharger a special after combustion chamber is not required. Theplant becomes therefore greatly simplified and relatively inexpensive.An additional advantage is that a part of the charged air can beemployed to improve the output of the engine. Auxiliary devices such asthe mechanically driven air delivery pump usually employed inconventional methods, become likewise unnecessary.

While specific embodiments of the invention have been shown anddescribed in detail to illustrate the application of the principles ofthe invention, it will be understood that the invention may be embodiedotherwise without departing from such principles.

What is claimed is:

1. Apparatus for the detoxification of the exhaust gases of an internalcombustion engine having an exhaust gas discharge line, said apparatuscomprising in combination, a twist generator connected to said dischargeline to receive the exhaust gas, said twist generator imparting a whirlto the exhaust gases and expanding the exhaust gases to a substantiallyreduced pressure for the discharge through an outlet; an air supply linecommunicating with said outlet for aspiration of combustion air into theexpanded exhaust gases at said outlet for admixture with the exhaustgases to provide a combustible gas-air mixture; and a diffusor connectedto said outlet to receive the combustible mixture for after-burning 0fthe toxic ingredients of the exhaust gases in said diffusor with anincrease of pressure of the products of combustion; said twist generatorcomprising the turbine of an exhaust gas turbo-supercharger; and acompressor driven by said turbine and supplying air to said air supplyline.

2. The apparatus according to claim 1, characterized in that only a partof the air supplied by said compressor is used for the after-combustion,while the remainder of said supplied air is directed to the engine forsupercharging.

3. The apparatus according to claim 1, characterized in that saidexhaust gas turbine (T) and said compressor (V) are arranged on a commonshaft and that the turbine (T) is designed as a substantially radialflowtype turbine with external inflow and axial outflow, said turbineincluding a rotor (5) actuable as a twist generator, said radialflow-type diffusor being disposed at the discharge outlet of saidturbine rotor.

1. Apparatus for the detoxification of the exhaust gases of an internalcombustion engine having an exhaust gas discharge line, said apparatuscomprising in combination, a twist generator connected to said dischargeline to receive the exhaust gas, said twist generator imparting a whirlto the exhaust gases and expanding the exhaust gases to a substantiallyreduced pressure for the discharge through an outlet; an air supply linecommunicating with said outlet for aspiration of combustion air into theexpanded exhaust gases at said outlet for admixture with the exhaustgases to provide a combustible gas-air mixture; and a diffusor connectedto said outlet to receive the combustible mixture for after-burning ofthe toxic ingredients of the exhaust gases in said diffusor with anincrease of pressure of the products of combustion; said twist generatorcomprising the turbine of an exhaust gas turbo-supercharger; and acompressor driven by said turbine and supplying air to said air supplyline.
 2. The apparatus according to claim 1, characterized in that onlya part of the air supplied by said compressor is used for theafter-combustion, while the remainder of said supplied air is directedto the engine for supercharging.
 3. The apparatus according to claim 1,characterized in that said exhaust gas turbine (T) and said compressor(V) are arranged on a common shaft and that the turbine (T) is designedas a substantially radial flow-type turbine with external inflow andaxial outflow, said turbine including a rotor (5) actuable as a twistgenerator, said radial flow-type diffusor being disposed at thedischarge outlet of said turbine rotor.